You’re getting a new sink installed in your kitchen soon. You already put a lot of time and effort into choosing the right style of sink and ensuring it meets your budget. Have you also determined whether the sink should be earthed?
According to regulations in the 15th Edition Wiring, if you have a steel sink with cold and hot pipework, there’s no need to add supplementary earth bonding. However, the mains gas pipework and the mains water pipework would require earthing. Some homeowners opt for gas meter and stop tap earthing as well.
If you’re a little unclear on what earthing even means in this context, you’re going to want to keep reading. We’ll tell you everything you need to know about kitchen sink earthing, from what it is, how it’s done, and when you need it.
Let’s get started!
What Does It Mean to Earth a Sink?
Before we proceed any further, let’s discuss the concept of earthing itself. This is also known as grounding.
Within your kitchen sink are a variety of pipes. If these are made of metal, such as cast iron or copper, then the possibility exists that electrical charges could be directed into your home through your sink. These electrical charges could lead to severe injury depending on the extent of the electrical power. Most sources of electrical charges as associated with the sink come from either static electricity or lightning strikes in a storm.
Thus, with some kitchen setups, to reduce the risk of potential electrical shock, your plumber will opt to earth the sink. This simply means redirecting these electrical charges to the ground from your home.
Let’s use a copper water pipe system as an example. This would be grounded due to the length of the pipes. Even though they attach to your kitchen sink, most water pipes can go several feet past their original point of installation. For instance, it’s not at all uncommon for cast iron or copper pipes to extend 10 feet into the ground from your main water line.
These days, plumbers have moved away from using cast iron and copper pipes, as well as other metal alternatives. Polyvinyl chloride, more commonly referred to as PVC, has replaced most of this metal.
Instead of using earthing or grounding exclusively, plumbers have also since switched to favoring dielectric unions as necessary. With a dielectric union, electrolysis rates are reduced through connecting pipes of two materials. The joints between the metal and PVC pipes don’t conduct electricity very well, which reduces the risk of injuries from electric shock.
Do Kitchen Sinks Need to Be Earthed?
Now that you understand earthing or grounding a little bit more clearly, that brings us back to your original question. If you proceed with your plans for a kitchen sink renovation, will that new sink have to be earthed?
As we said in the intro, the answer is more than likely no. The guidelines towards earthing kitchen sinks were published in the 15th Edition, which is produced by the Institution of Engineering and Technology or IET. The IET regulations follow British Standards and first entered publication in 1882. The regulations have been frequently updated ever since. All plumbers not only need to learn the rules published by the IET, but keep up with the changes that can and do occur.
For instance, the IET has since published the 18th Edition of its regulations, but we mentioned the 15th edition specifically because that was the first to recently amend which kitchen sinks needed to be earthed.
To reiterate from the intro, if you have a stainless steel sink with metal piping, then you don’t need supplementary earth bonding to the cold and hot metal pipework. If you have mains gas pipework and mains water pipework, the IET mandates that these include the protection of a residual-current device or RCD as well as earth bonding. Gas meter and water stop tap earthing are also recommended.
What’s an RCD? Also known as a residual-current circuit breaker or RCCB in the UK, an RCD goes by names like appliance leakage current interrupter or ALCI, ground fault interrupter or GFI, or ground fault circuit interrupter or GFCI in Canada and the United States.
No matter what you want to call it, an RCD is a type of device for breaking up electrical circuits before they can cause injury from shocks. They’re not completely foolproof, as homeowners with RCDs have been harmed in the past if they put their hands near the two conductors, but otherwise, RCDs are a great safety precautionary measure.
Here’s how the RCD works. When an electrical current comes through that’s not evenly balanced from a circuit’s return and supply conductors, the RCD turns that circuit off immediately. This prevents current leakage that could cause shocks and hurt you.
What about earth bonding? That’s been recommended for steel sinks since the 15th published edition of the IET’s guidelines, so what does this mean?
Although you might think that PVC and other non-metal pipes would conduct electricity less readily, that’s not necessarily the case. As liquids travel through PVC pipes, friction develops, which can build up into a static charge. Also, electrical grounding sources may be interrupted by non-metal pipes, which can also put you at risk of shock.
Thus, that’s why a plumber might recommend earth bonding for some kitchen sinks. With earth bonding, a non-corrosive grounding wire acts as the bonding between the electrical system and the non-metal plumbing system while a secondary electrode grounds them.
The grounding wire starts at any metal pipes and travels to the main electrical panel’s metal box before ending at the grounding rod. In bonding the pipes like this, the metal wire is now a circuit that can transport electrical charges towards the ground rather than let the charges stay within your piping system.
How to Earth a Kitchen Sink
This next section is for educational purposes only. Unless you’re a registered plumber, it’s really not a good idea to go messing around with the pipework in your kitchen sink. You could severely hurt yourself, such as through electrical shock, not to mention you could accidentally ruin your sink too!
That said, for curiosity’s sake, here’s a video courtesy of How2D2 on YouTube that shows how to earth a sink with copper pipe.
The video has no instructions, but we’ll provide some steps you’d follow.
Step 1: Make sure you buy new clamps, specifically earth clamps so you can attach the wire to the basin pipes and bath pipes.
Step 2: Clean the pipe if you haven’t already done so, as it’s better to work with a clean pipe when installing the earth clamps.
Step 3: The clamps should attach to the pipe with no difficulty. The screwed-on metal tabs attached to the earth clamps pull out to reinforce the clamp to the kitchen sink pipe. Pliers will secure the tabs and make them even tighter.
Step 4: Tighten any loose screws, especially at the clamp’s knot, as this will keep the setup reinforced and ready to use.
Step 5: Attach your earth wire to the earth clamps. With a Stanley knife, you can remove some of the earth wire’s insulation to make the connection easier, but make sure you don’t strip the earth wire too much!
Those five steps should reinstate the earth bonding. Just to repeat, we’re not recommending you go out and earth your kitchen sink pipes yourself if the job must be done. It’s much better and safer to call a professional instead.
Earthing, which is also known as grounding, prevents unwanted electrical charges from static buildup or thunderstorms from harming you when using your sink. In your kitchen especially, you shouldn’t need to have your stainless steel sink earthed, at least according to recommendations and guidelines from the IET. Supplemental earthing may be necessary in some instances though.
Now that you’ve learned about earthing, you can continue with your kitchen sink renovation knowing it’ll be functional, beautiful, and–above all–safe. Good luck!